Modal Verbs – ISE II Trinity Grammar Function
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Modals (also called modal verbs, modal auxiliary verbs, modal auxiliaries) are special verbs which behave irregularly in English. They are different from normal verbs like “work, play, visit…” They give additional information about the function of the main verb that follows it. They have a great variety of communicative functions.
Here are some characteristics of modal verbs:
- They never change their form. You can’t add “s”, “ed”, “ing”…
- They are always followed by an infinitive without “to” (e.i. the bare infinitive.)
- They are used to indicate modality allow speakers to express certainty, possibility, willingness, obligation, necessity, ability
| Modal Verb | Expressing | Example |
|---|---|---|
| must | Strong obligation | You must stop when the traffic lights turn red. |
| logical conclusion / Certainty | He must be very tired. He’s been working all day long. | |
| must not | prohibition | You must not smoke in the hospital. |
| can | ability | I can swim. |
| permission | Can I use your phone please? | |
| possibility | Smoking can cause cancer. | |
| could | ability in the past | When I was younger I could run fast. |
| polite permission | Excuse me, could I just say something? | |
| possibility | It could rain tomorrow! | |
| may | permission | May I use your phone please? |
| possibility, probability | It may rain tomorrow! | |
| might | polite permission | Might I suggest an idea? |
| possibility, probability | I might go on holiday to Australia next year. | |
| need not | lack of necessity/absence of obligation | I need not buy tomatoes. There are plenty of tomatoes in the fridge. |
| should/ought to | 50 % obligation | I should / ought to see a doctor. I have a terrible headache. |
| advice | You should / ought to revise your lessons | |
| logical conclusion | He should / ought to be very tired. He’s been working all day long. | |
| had better | advice | You ‘d better revise your lessons |
Modal Verbs – ISE II Trinity Grammar Function
Remember
Modal verbs are followed by an infinitive without “to”, also called the bare infinitive.
Examples:
- You must stop when the traffic lights turn red.
- You should see to the doctor.
- There are a lot of tomatoes in the fridge. You need not buy any.
Modals in the present and past
Generally speaking modals in the past have the following form:
- modal + have + past participle
- Present:
You should see a doctor.- Past:
You should have seen a doctorExcept for modals that express obligation,ability and lack of necessity:
- Obligation:
Present = I must / have to work hard. — Past = I had to work hard.- Ability:
Present = I can run fast. — Past = I could run fast when I was young.- Lack of necessity:
Present = You don’t have to / needn’t take your umbrella. — Past = You didn’t have to / didn’t need to take your umbrella.
Modals in the Present Modals in the Past Obligation You must / have to stop when the traffic lights are red. You had to stop. Advice You should see a doctor. You should have seen a doctor Prohibition You mustn’t smoke here. You mustn’t have smoked there. Ability I can run fast. I could run fast. now I am old. Certainty He has a Rolls Royce. He must be very rich.
He can’t be American. His English is terrible.He must have been rich. He had a big house and an expensive car.
He can’t have written that poem. He was illiterate.Permission Can I go out? She could drive her father’s car when she was only 15. Possibility It may / can / could / might rain. It’s cloudy. I guess it may / can / could / might have been Lacy on the phone. Lack of necessity You don’t have to / needn’t buy any tomatoes. There are plenty in the fridge. You didn’t have to / didn’t need to buy tomatoes.
Modal Verbs – ISE II Trinity Grammar Function
